Determination of Glycyrrhetic Acid in Rat Plasma by HPLC After Oral Administration of Licorice Aqueous Extract

Licorice is obtained from Glycyrrhiza glabra (G. glabra) in Iran. Glycyrrhizin is the main constituent of G. glabra and has several pharmacological effects. It is hydrolyzed to glycyrrhetic acid (GA) in the intestine after oral administration. In this study, a novel HPLC method was used to determine the concentration of GA in rat plasma after oral administration of licorice aqueous extract. The method was linear (r2 >0.999) in the range of 0.1-5.0 μg/ml for GA. Maximum plasma concentration of GA was achieved 8 h after oral administration of licorice aqueous extract. The developed method was suitable for determination of GA in rat plasma.